U.S. patent application number 10/594069 was filed with the patent office on 2007-08-23 for device and method for joining substrates.
Invention is credited to Kazuo Okutsu, Kosuke Takasaki, Koji Tsujimura, Kiyofumi Yamamoto.
Application Number | 20070194438 10/594069 |
Document ID | / |
Family ID | 35056478 |
Filed Date | 2007-08-23 |
United States Patent
Application |
20070194438 |
Kind Code |
A1 |
Takasaki; Kosuke ; et
al. |
August 23, 2007 |
Device And Method For Joining Substrates
Abstract
A device for joining substrates (11) is provided inside a clean
booth (12). a single axis robot (46) and a five axis robot (47)
convey a wafer (25) and a glass substrate (33). A transcribing
station (91) obtains a transcribing film (112) on which adhesive is
applied from a film supplying section (113), and presses the
transcribing film (112) to the glass substrate (33) so as to
transcribe the adhesive to the glass substrate (33). A peeling
station (92) peels the transcribing film (112) from the glass
substrate (33). A joining station (57) positions the wafer (25) and
the glass substrate (33), adjusts parallelism of joining surfaces
of the wafer (25) and the glass substrate (33), and joins these
substrates together. Since the handling and the joining of the
wafer (25), the glass substrate (33) and the transcribing film
(112) are performed in the clean booth, it is prevented that a
yield ratio of the product decreases because of the adhesion of
foreign matters.
Inventors: |
Takasaki; Kosuke; (Kanagawa,
JP) ; Yamamoto; Kiyofumi; (Kanagawa, JP) ;
Okutsu; Kazuo; (Kanagawa, JP) ; Tsujimura; Koji;
(Kanagawa, JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
SUITE 800
WASHINGTON
DC
20037
US
|
Family ID: |
35056478 |
Appl. No.: |
10/594069 |
Filed: |
March 23, 2005 |
PCT Filed: |
March 23, 2005 |
PCT NO: |
PCT/JP05/05999 |
371 Date: |
September 26, 2006 |
Current U.S.
Class: |
257/704 ;
257/E31.117 |
Current CPC
Class: |
H01L 27/14618 20130101;
H01L 27/14632 20130101; H01L 2924/0002 20130101; H01L 21/67778
20130101; H01L 21/681 20130101; H01L 31/0203 20130101; H01L 2924/00
20130101; H01L 2221/68395 20130101; H01L 27/14687 20130101; H01L
2924/0002 20130101; H01L 21/67766 20130101; H01L 21/67132
20130101 |
Class at
Publication: |
257/704 |
International
Class: |
H01L 23/12 20060101
H01L023/12 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 26, 2004 |
JP |
2004-093628 |
Sep 28, 2004 |
JP |
2004-281895 |
Claims
1. A device for joining substrates which is used for manufacturing
a chip size package formed in a way that a semiconductor substrate
with plural elements formed thereon and a sealing substrate for
individually sealing said elements are joined together and diced
into a plurality of said chip size packages having said individual
sealed element, comprising: a substrate supplying section for
supplying said semiconductor substrate and said sealing substrate;
a transcribing sheet supplying section for supplying an elastic
transcribing sheet on which adhesive is coated; a transcribing
sheet pressurization section for pressurizing together a joint
surface of said transcribing sheet coated with said adhesive and a
joint surface of said sealing substrate; a transcribing sheet
peeling section for peeling said transcribing sheet from said
sealing substrate so as to form a layer of said adhesive on said
sealing substrate; a parallelism adjusting section for adjusting
parallelism of said joint surface of said semiconductor substrate
and said joint surface of said sealing substrate on which said
adhesive layer is formed; a substrate joining section for adjusting
positions of said semiconductor substrate and said sealing
substrate, and then joining said semiconductor substrate and said
sealing substrate which are adjusted their positions; and a
substrate conveying mechanism for conveying said semiconductor
substrate, said sealing substrate and said transcribing sheet among
said respective sections.
2. A device for joining substrates as described in claim 1, wherein
said chip size package is a solid state imaging device, and said
sealing substrate is formed of a transparent material.
3. A device for joining substrates as described in claim 2, wherein
said element is an image sensor, and said sealing substrate is
constituted of a glass substrate and plural flame-like spacers
which individually surround said image sensors.
4. A device for joining substrates as described in claim 1, wherein
said transcribing sheet peeling section comprises: a peeling roller
provided close to one end of said sealing substrate which is set at
a position for peeling said transcribing sheet; a long adhesive
tape being hanged on said peeling roller and contacting to one end
of said transcribing sheet; a roller moving mechanism for moving
said peeling roller from a position near said one end of said
sealing substrate to a position near another end of said sealing
substrate; and a winding section for winding said adhesive tape in
synchronization with move of said peeling roller by said roller
moving mechanism so as to keep a constant angle between said peeled
transcribing sheet and said joint surface of said sealing
substrate.
5. A device for joining substrates as described in claim 4, said
transcribing sheet peeling section further comprising: a roller
clearance adjusting mechanism for moving said peeling roller so as
to adjust clearance between said peeling roller and said
transcribing sheet before peeled, in a direction perpendicular to
said joint surface of said sealing substrate which is set at a
position for being joined with said transcribing sheet.
6. A device for joining substrates as described in claim 4, a
clearance between an outer peripheral surface of said adhesive tape
hanged on said peeling roller and said transcribing sheet being 0.1
mm or less when said transcribing sheet is peeled.
7. A device for joining substrates as described in claim 4, wherein
said peeling roller has a diameter of between 15 mm and 20 mm.
8. A device for joining substrates as described in claim 1, wherein
said transcribing sheet is an antistatic plastic film.
9. A device for joining substrates as described in claim 1, wherein
said transcribing sheet pressurization section pressurizes said
transcribing sheet through a cushion.
10. A device for joining substrates as described in claim 9,
wherein said cushion is a sponge rubber having hardness of ASKER-C
20-40.
11. A device for joining substrates as described in claim 1, said
parallelism adjusting section comprising: a plurality of substrate
clearance measurement section for measuring clearances between said
joint surface of said semiconductor substrate and said joint
surface of said sealing substrate at plural measurement points; and
a substrate inclination adjusting section for adjusting
inclinations of said semiconductor substrate or said sealing
substrate based on measurement result from said substrate clearance
measurement section.
12. A device for joining substrates as described in claim 11,
wherein said substrate clearance measurement section comprises: a
plurality of transmission illuminating devices for emitting
transmission light to said measurement points between said joint
surface of said semiconductor substrate and said joint surface of
said sealing substrate; a plurality of substrate clearance imaging
devices provided corresponding to said transmission illuminating
devices, for imaging said semiconductor substrate and said sealing
substrate which are illuminated at said measurement points; and a
substrate clearance calculating device for calculating lengths of
said clearances between said joint surfaces of said semiconductor
substrate and said sealing substrate at said measurement points by
analyzing image data from said plurality of substrate clearance
imaging devices.
13. A device for joining substrates as described in claim 12,
wherein said transmission illuminating device has a converging
angle of 1.degree. or less.
14. A device for joining substrates as described in claim 12,
wherein said substrate clearance imaging device has a telecentric
lens which only parallel lights can enter.
15. A device for joining substrates as described in claim 11,
wherein said substrate clearance measurement section has a laser
measurement device for measuring distance between said joint
surface of said semiconductor substrate and said joint surface of
said sealing substrate at predetermined points.
16. A device for joining substrates as described in claim 11,
wherein said substrate inclination adjusting section comprises: a
plurality of actuators positioned corresponding to said measurement
positions of said substrate clearance measurement section, for
moving plural predetermined positions of said semiconductor
substrate or said sealing substrate in perpendicular direction of
said joint surface; an actuator controller for controlling said
actuators based on measurement result from said substrate clearance
measurement section; and a plate supporting mechanism for swingably
supporting either one of said semiconductor substrate and said
sealing substrate to follow the other substrate when joining said
semiconductor substrate and said sealing substrate, with swing
reference of said supported substrate being in the same plane as
said joint surface of said supported substrate.
17. A device for joining substrates as described in claim 1,
wherein said parallelism adjusting section comprises: a plurality
of displacement amount measuring section for measuring displacement
amounts of said joint surface of said semiconductor substrate and
said joint surface of said sealing substrate at plural measurement
points from predetermined reference positions in a direction
perpendicular to said joint surfaces; and a substrate inclination
adjusting section for adjusting inclinations of said semiconductor
substrate or said sealing substrate based on measurement result
from said displacement amount measuring section.
18. A device for joining substrates as described in claim 17,
wherein said substrate inclination adjusting section comprises: a
plurality of actuators positioned corresponding to said measurement
positions of said displacement amount measuring section, for moving
plural predetermined positions of said semiconductor substrate or
said sealing substrate in perpendicular direction of said joint
surface; an actuator controller for controlling said actuators
based on measurement result from said displacement amount measuring
section; and a plate supporting mechanism for swingably supporting
either one of said semiconductor substrate and said sealing
substrate to follow the other substrate when joining said
semiconductor substrate and said sealing substrate, with swing
reference of said supported substrate being in the same plane as
said joint surface of said supported substrate.
19. A device for joining substrates as described in claim 1,
wherein said parallelism adjusting section comprises: a support
plate for holding said semiconductor substrate or said sealing
substrate; and a plate holding mechanism for holding said support
plate in a swingable manner with said semiconductor substrate and
said sealing substrate contacting each other, and for fixing said
support plate said supported substrate swings to follow said other
substrate.
20. A device for joining substrates as described in claim 19,
wherein said plate holding mechanism comprises: a spherical shaft
integrated with said support plate; a spherical receiver for
swingably supporting said spherical shaft; and an air pump for
sending air in between said spherical shaft and said spherical
receiver so as to allow movement of said spherical shaft, and for
sucking said air from between said spherical shaft and said
spherical receiver so as to fix said spherical shaft on said
spherical receiver.
21. A device for joining substrates as described in claim 1,
wherein said substrate joining section comprises: an underside
support plate for holding said sealing substrate or said
semiconductor substrate; a position adjusting section for moving
said underside support plate in a plane direction and a rotational
direction so as to adjust positions of said sealing substrate and
said semiconductor substrate; a topside support plate positioned
above and faced to said underside support plate, for holding said
sealing substrate whose position is adjusted so as to face said
underside support plate; and a pressure mechanism for pressing said
underside support plate toward said topside support plate when said
semiconductor substrate and said sealing substrate are joined.
22. A device for joining substrates as described in claim 21,
wherein said pressure mechanism has a pressure control mechanism
for controlling pressure of said pressure mechanism so as not to
exceed a predetermined value.
23. A device for joining substrates as described in claim 1,
wherein said adhesive on said transcribing sheet is light-delayed
curing adhesive, and said device for joining substrates further
comprises an illumination station for irradiating light to start
the curing of said adhesive before said adhesive is transcribed
onto said sealing substrate.
24. A device for joining substrates as described in claim 1,
wherein said device for joining substrates is set inside a clean
booth which is sealed from outside.
25. A method for joining substrates which is used for manufacturing
a chip size package formed in a way that a semiconductor substrate
with plural elements formed thereon and a sealing substrate for
individually sealing said elements are joined together and diced
into a plurality of said chip size packages having said individual
sealed element, comprising steps of: (a) supplying a semiconductor
substrate; (b) supplying a sealing substrate; (c) supplying an
elastic transcribing sheet on which adhesive is coated; (d)
pressurizing together a joint surface of said transcribing sheet
coated with said adhesive and a joint surface of said sealing
substrate; (e) peeling said transcribing sheet from one end of said
sealing substrate with maintaining a constant curvature so as to
form a layer of said adhesive on said sealing substrate; (f)
adjusting parallelism of said joint surfaces of said semiconductor
substrate and said sealing substrate; (g) adjusting positions of
said semiconductor substrate and said sealing substrate; and (h)
joining said semiconductor substrate and said sealing substrate
which are adjusted their positions.
26. A method for joining substrates described in claim 25, wherein
said step (f) further includes steps of: (f1) measuring clearances
between said joint surface of said semiconductor substrate and said
joint surface of said sealing substrate at plural measurement
points; and (f2) adjusting inclinations of said semiconductor
substrate or said sealing substrate based on result of said
measurement.
27. A method for joining substrates described in claim 25, wherein
said step (f) further includes steps of: (f1) measuring respective
positions of said joint surface of said semiconductor substrate and
said joint surface of said sealing substrate at plural measurement
points in a direction perpendicular to said joint surfaces; (f2)
calculating parallelism between said semiconductor substrate and
said sealing substrate by comparing said measured positions at said
plural measurement points to preset reference positions; and (f3)
adjusting inclinations of said semiconductor substrate or said
sealing substrate based on result of said calculation.
28. A method for joining substrates described in claim 25, wherein
said step (f) further includes steps of: (f1) movably holding a
movable plate which holds said semiconductor substrate or said
sealing substrate; (f2) contacting said semiconductor substrate to
said sealing substrate each other such that said substrate held by
said movable plate follows said other substrate held by a
stationary plate; and (f3) fixing said movable plate.
29. A method for joining substrates described in claim 26, wherein
said step (f1) further includes steps of: (f11) making said joint
surfaces of said semiconductor substrate and said sealing substrate
face each other with predetermined clearance; (f12) emitting
transmission light to said measurement points between said joint
surface of said semiconductor substrate and said joint surface of
said sealing substrate, and imaging said semiconductor substrate
and said sealing substrate which are illuminated at said
measurement points; and (f13) calculating lengths of said
clearances between said joint surfaces of said semiconductor
substrate and said sealing substrate at said measurement points by
analyzing image data obtained from said imaging.
30. A method for joining substrates described in claim 26, wherein
said step (f1) further includes steps of: (f11) making said joint
surfaces of said semiconductor substrate and said sealing substrate
face each other with predetermined clearance; (f12) detecting
lengths of said clearances between said joint surfaces of said
semiconductor substrate and said sealing substrate such that plural
light emitting sections respectively emit laser beam to go through
between said joint surfaces of said semiconductor substrate and
said sealing substrate toward corresponding light receiving
section.
31. A method for joining substrates described in claim 26, wherein
said step (f3) further includes a step of swinging either one of
said semiconductor substrate and said sealing substrate to follow
the inclination of said other substrate in the same plane as said
joint surface of said substrate.
Description
TECHNICAL FIELD
[0001] The present invention relates to a device and a method for
joining a semiconductor substrate and a sealing substrate when
producing a chip size package.
BACKGROUND ART
[0002] A digital camera and a digital video camera with use of a
solid state imaging device such as a CCD, a CMOS, and the like is
in widespread use. A conventional solid state imaging device has a
structure that an image sensor chip which is a semiconductor
substrate is contained in a package and is sealed by a transparent
glass rid. However, because of increasing demand for a mobile phone
with the image-taking function and the like, the solid state
imaging device is required to be small.
[0003] As a packaging method to downsize the solid state imaging
device, a wafer-level chip size package (hereinafter WLCSP) is
known. In the WLCSP, a semiconductor device is obtained by dicing a
wafer after the packaging is completed in a semiconductor wafer
process. A solid state imaging device manufactured by the WLCSP has
the same size same as a bare chip.
[0004] Examples of the solid state imaging devices of WLCSP type
are disclosed in Japanese Patent Laid-Open Publications No.
2002-329850 and No. 2003-163342, and a prior application of the
applicant (Japanese Patent Application No. 2003-320271). In the
Japanese Patent Laid-Open Publication No. 2002-329850, the solid
state imaging device is formed in a way that a transparent cover
glass is adhered on a frame which is formed of lamination of
insulating resin and electrodes to surround an image sensor, so as
to seal the image sensor. And a space between the image sensor and
the cover glass is provided such that the condensing performance of
the micro lens does not become worse.
[0005] In the Japanese Patent Laid-Open Publication No.
2003-163342, the solid state imaging device is formed such that a
frame is formed by coating adhesive including filler around an
image sensor, and then a transparent cover glass is adhered on the
frame so as to seal the image sensor. And between the image sensor
and the cover glass, a space determined by a diameter of the filler
is provided. In the Japanese Patent Application No. 2003-320271,
the solid state imaging device is formed such that a spacer as a
frame surrounds an image sensor and a transparent cover glass is
adhered on the spacer so as to seal the image sensor with
appropriate space between the image sensor and the cover glass.
[0006] The solid state imaging devices described above are
manufactured as described below. First, plural frames are formed on
a transparent glass substrate which is a base material of the cover
glass. Material of these frames is the insulating resin and the
electrodes in the Japanese Patent Laid-Open Publication No.
2002-329850, while the adhesive including filler in the Japanese
Patent Laid-Open Publication No. 2003-163342. In the Japanese
Patent Application No. 2003-320271, the spacers are formed on the
glass substrate and adhesive is applied on an end surface of the
spacers. Next, the glass substrate and a wafer on which the plural
image sensors and contact terminals are formed are joined such that
the each image sensor is sealed by the frame and the glass
substrate. Then the glass substrate with the wafer is diced into a
plurality of the solid state imaging devices.
[0007] To increase the yield of the solid state imaging device
manufacture, the wafer and the glass substrate should be free from
sticking of the foreign matters. However, in the manufacturing
methods of the Japanese Patent Laid-Open Publication No.
2002-329850 and No. 2003-163342 and the Japanese Patent Application
No. 2003-320271, each manufacturing process is separated and the
work needs to be transferred among respective manufacturing
processes by human hands. Therefore, it is difficult to prevent
that the foreign matters stick to the work.
[0008] In addition, in a process for coating the adhesive, the
glass substrate is highly possible to be messed. However, in the
Japanese Patent Laid-Open Publication No. 2002-329850, there is no
statement about the process for coating the adhesive, therefore the
possibility of messing the glass substrate in the coating process
is not considered. In the Japanese Patent Laid-Open Publication No.
2003-163342, the adhesive including filler is coated on the glass
substrate by printing. This method has problems that alignment of
the printing position and control of coating thickness are very
difficult. When the application quantity is not appropriate, it
ends up with defective sealing. Further, it is possible that the
adhesive slides or sticks to a portion of the glass substrate which
faces to the image sensor at the time of printing, which leads to
decrease in the yield ratio. In addition, if silicon is used as a
material of the surface on which the adhesive is coated, there is
possibility that the silicon sheds the adhesive because the silicon
has bad wettability to the adhesive.
[0009] In the Japanese Patent Application No. 2003-320271, a
transcribing film on which the adhesive is coated at constant
thickness as an adhesive layer is superimposed on the glass
substrate, and then the transcribing film is rolled up to be peeled
off from top end of the glass substrate, such that the adhesive
layer is transcribed on the spacers on the glass substrate.
Accordingly, it is easy to control the coating thickness of the
adhesive.
[0010] However, in the Japanese Patent Application No. 2003-320271,
the plastic film is peeled by human hands. Therefore, there are
problems that curvature of the transcribing film and angle between
the film and the transcribing film, both of which largely affect
performance of the peeling, are unstable in peeling. For example,
if the curvature of the transcribing film is too small, the peeling
cannot be performed smoothly. If the curvature is too large,
membrane of the adhesive is created between the transcribing film
and the spacer. The membrane bursts and splashes to mess the glass
substrate when exceeds the viscosity of the adhesive.
[0011] In addition, if the wafer and the glass substrate are not in
parallel with facing each other at the time of joining, their
joining positions become misaligned. For example, when a
parallelism between two 6-inch wafers is 60 .mu.m, a misaligned
distance between two wafers becomes 10 .mu.m. In the solid state
imaging device which has small size, the distance between the image
sensor and the frame is also small. Accordingly, the adhesive flows
to the image sensor and the contact terminals when the joining
positions are slightly misaligned that causes deterioration of the
yield. Therefore, the misaligned distance between the wafer and the
glass substrate needs to be few micrometers or less. For satisfying
the requirement, the parallelism between the two substrates needs
to be 10 .mu.m or less.
[0012] For adjusting the parallelism of the substrates 10 .mu.m or
less, the parallelism needs to be measured. As stated above, for
preventing the sticking of foreign matters, the parallelism
measurement should be performed in a non-contact way.
Conventionally, the non-contact parallelism measurement is
performed by laser displacement gauges. However, the solid state
imaging device of WLCSP type, which uses opaque material for the
spacer, can not be measured in parallelism by using the laser
displacement gauges. Note that the Japanese Patent Laid-Open
Publication No. 2002-329850 and No. 2003-163342 and the Japanese
Patent Application No. 2003-320271 do not describe solutions for
these problems in joining the substrates.
[0013] An object of the present invention is to provide a device
and a method for joining a wafer (semiconductor substrate) and a
glass substrate (sealing substrate) with high yield ratio.
DISCLOSURE OF INVENTION
[0014] In order to achieve the object, a device for joining
substrates of the present invention comprises a substrate supplying
section for supplying a semiconductor substrate and a sealing
substrate, a transcribing sheet supplying section for supplying an
elastic transcribing sheet on which adhesive is coated, a
transcribing sheet pressurization section for pressurizing together
a joint surface of the transcribing sheet on which the adhesive is
coated and a joint surface of the sealing substrate, a transcribing
sheet peeling section for peeling the transcribing sheet from the
sealing substrate so as to form an adhesive layer on the sealing
substrate, a parallelism adjusting section for adjusting
parallelism of the joint surface of the semiconductor substrate and
the joint surface of the sealing substrate on which the adhesive
layer is formed, a substrate joining section for adjusting
positions of the semiconductor substrate and the sealing substrate
and then joining the semiconductor substrate and the sealing
substrate which are adjusted their positions, and a substrate
conveying mechanism for conveying the semiconductor substrate, the
sealing substrate and the transcribing sheet among the respective
sections. If an image sensor is formed on the semiconductor
substrate, the sealing substrate is formed of a transparent
material.
[0015] In a preferred embodiment, the transcribing sheet peeling
section comprises a peeling roller provided close to one end of the
sealing substrate which is set at a position for peeling the
transcribing sheet, a long adhesive tape being hanged on the
peeling roller and contacting one end of the transcribing sheet, a
roller moving mechanism for moving the peeling roller from a
position near the one end of the sealing substrate to a position
near another end of the sealing substrate, and a winding section
for winding the adhesive tape in synchronization with the move of
the peeling roller by the roller moving mechanism so as to keep a
constant angle between the peeled transcribing sheet and the joint
surface of the sealing substrate.
[0016] The transcribing sheet peeling section further comprises a
roller clearance adjusting mechanism for adjusting clearance
between the peeling roller and the transcribing sheet before being
peeled. It is preferable that a clearance between an outer
peripheral surface of the adhesive tape hanged on the peeling
roller and the transcribing sheet is 0.1 mm or less when the
transcribing sheet is peeled. It is preferable that a diameter of
the peeling roller is between 15 mm and 20 mm.
[0017] As the transcribing sheet, an antistatic plastic film is
used. In addition, the transcribing sheet pressurization section
pressurizes the transcribing sheet through a cushion. As the
cushion, a sponge rubber having hardness of ASKER-C 20-40 is
preferably used.
[0018] The parallelism adjusting section comprises a plurality of
substrate clearance measurement section for measuring clearance
between the joint surface of the semiconductor substrate and the
joint surface of the sealing substrate at plural measurement points
and a substrate inclination adjusting section for adjusting
inclination of the semiconductor substrate or the sealing substrate
based on measurement result from the substrate clearance
measurement section.
[0019] The substrate clearance measurement section comprises a
plurality of transmission illuminating devices for emitting
transmission light to the measurement points between the joint
surface of the semiconductor substrate and the joint surface of the
sealing substrate, a plurality of substrate clearance imaging
devices provided corresponding to the transmission illuminating
devices for imaging the semiconductor substrate and the sealing
substrate which are illuminated at the measurement points, and a
substrate clearance calculating device for calculating length of
the clearance between the joint surfaces of the semiconductor
substrate and the sealing substrate at the measurement points by
analyzing image data from the plurality of substrate clearance
imaging devices. It is preferable that the transmission
illuminating device has a converging angle of 1.degree. or less. In
addition, it is preferable that the substrate clearance imaging
device has a telecentric lens in which only the parallel lights can
enter.
[0020] Another substrate clearance measurement section has a laser
measurement device for measuring distance between the joint surface
of the semiconductor substrate and the joint surface of the sealing
substrate at predetermined points.
[0021] Another parallelism adjusting section comprises a plurality
of displacement amount measuring section for measuring displacement
amounts of the joint surface of the semiconductor substrate and the
joint surface of the sealing substrate from predetermined reference
positions in a direction perpendicular to the joint surfaces at
plural measurement points, and a substrate inclination adjusting
section for adjusting inclination of the semiconductor substrate or
the sealing substrate based on measurement result from the
displacement amount measuring section.
[0022] The substrate inclination adjusting section comprises a
plurality of actuators positioned corresponding to the measurement
positions of the measuring section, for moving plural predetermined
positions of the semiconductor substrate or the sealing substrate
in a perpendicular direction of the joint surface, an actuator
controller for controlling the actuators based on measurement
result from the measuring section, and a plate supporting mechanism
for swingably supporting either one of the semiconductor substrate
and the sealing substrate to follow the other substrate when the
semiconductor substrate and the sealing substrate are joined, with
the swing reference of movement of the supported substrate being in
the same plane as the joint surface of the supported substrate.
[0023] Further alternative parallelism adjusting section comprises
a support plate for holding the semiconductor substrate or the
sealing substrate, and a plate holding mechanism for holding the
support plate in a swingable manner with the semiconductor
substrate and the sealing substrate contacting each other, and for
fixing the support plate a fixed manner after the supported
substrate swings to follow the other substrate.
[0024] The plate holding mechanism comprises a spherical shaft
integrated with the support plate, a spherical receiver for
swingably supporting the spherical shaft, and an air pump for
sending air in between the spherical shaft and the spherical
receiver so as to allow movement of the spherical shaft and for
sucking the air from between the spherical shaft and the spherical
receiver so as to fix the spherical shaft.
[0025] In addition, for controlling viscosity of the adhesive,
light-delayed curing adhesive may be used as the adhesive, and an
illumination station may be provided for irradiating light to start
the curing of the adhesive.
[0026] According to the present invention, a method for joining
substrates comprises steps of supplying a semiconductor substrate,
supplying a sealing substrate, supplying an elastic transcribing
sheet on which adhesive is applied, pressurizing together a joint
surface of the transcribing sheet coated with the adhesive and a
joint surface of the sealing substrate, peeling the transcribing
sheet from one end of the sealing substrate with maintaining a
constant curvature so as to form an adhesive layer on the sealing
substrate, adjusting parallelism of the joint surfaces of the
semiconductor substrate and the sealing substrate, adjusting
positions of the semiconductor substrate and the sealing substrate,
and joining the semiconductor substrate and the sealing substrate
which are adjusted their positions.
[0027] The step of adjusting parallelism of the joint surfaces of
the semiconductor substrate and the sealing substrate includes
steps of measuring clearance between the joint surface of the
semiconductor substrate and the joint surface of the sealing
substrate at plural measurement points, and adjusting inclinations
of the semiconductor substrate or the sealing substrate based on
the measurement result.
[0028] The step of measuring length of clearance between the joint
surfaces of the semiconductor substrate and the sealing substrate
includes steps of making the joint surfaces of the semiconductor
substrate and the sealing substrate face each other with
predetermined clearance, emitting transmission light and imaging
plural positions between the joint surfaces of the semiconductor
substrate and the sealing substrate, and calculating lengths of the
clearances between the joint surfaces of the semiconductor
substrate and the sealing substrate by analyzing image data
obtained from the imaging.
[0029] The step of adjusting inclination of the substrate includes
a step of swinging either one of the semiconductor substrate or the
sealing substrate to follow the other substrate, in the same level
as the joint surface of the substrate.
[0030] Since the feeding of the semiconductor substrate, the
sealing substrate and the transcribing sheet, and the coating the
adhesive are performed not with human hands according to the device
and method for joining substrates of the present invention, foreign
matters do not stick to the substrates. Since the peeling of the
transcribing sheet with the curvature and angle of the peeling
maintained constant is automatically performed by the transcribing
sheet peeling section, it is prevented that the substrates are
messed with membrane of the adhesive created at the time of the
peeling of the transcribing sheet.
[0031] Since the curvature of the peeling of the transcribing sheet
is determined by the peeling roller, it can be maintained constant
through the peeling. In addition, because the curvature can be
modified by moving the peeling roller in the direction of the joint
surface or changing the peeling roller with another peeling roller
which has another diameter, the condition of the peeling can be
adjusted adequately.
[0032] Since the long adhesive tape is used for peeling the
transcribing sheet, the transcribing sheet can be easily and less
costly held without the use of complicated mechanisms, and the
peeling angle of the transcribing sheet can be easily controlled.
Also, because the peeled transcribing film can be wound with the
used adhesive tape, complicated mechanisms or devices for
processing the peeled transcribing film are not required. In
addition, because the new adhesive tape is supplied at the same
time as the used adhesive tape is wound, efficiency in the
production of chip size packages is improved.
[0033] In addition, an antistatic plastic film is used as the
transcribing sheet, and it can prevents the transcribing sheet from
sticking to portions not relate to handling of the sheet in the
device and thereby from hindering the transportation of the
transcribing sheet. In addition, since the transcribing sheet is
pressed to the sealing substrate through the cushion, it is
prevented that the adhesive flows out from the spacer by excessive
pressure of the transcribing sheet.
[0034] Since the parallelism measurement for the parallelism
adjustment is performed in a non-contact manner by the substrate
clearance measurement section, the displacement amount measuring
section or the laser measurement device, it is prevented that the
semiconductor substrate and the sealing substrate are messed with
the measuring instruments. Further, the clearance between the
substrates can be precisely measured because the clearance is
illuminated by transmission light for imaging, and the distance of
the clearance is calculated based on the image data obtained by the
imaging. In addition, since the converging angle of the
transmission light is 1.degree. or less, and the telecentric lens
is used, the measurement is not influenced by light reflected on
the joint surfaces of the substrates. Accordingly, the clearance
can be precisely measured even if the measurement position of the
substrates is apart from a focus position of an imaging camera. The
efficiency in the production of the package can be more improved
because there is no need to precisely adjust the focus position of
the imaging camera and the measurement position of the
substrates.
[0035] Because the plate supporting mechanism of the substrate
inclination adjusting section swings the substrate with the swing
reference of the supported substrate being in the same level as the
joint surface of the supported substrate, therefore misalignment of
the joining position between the substrates, which is caused by
movement of the supported substrate, can be minimized.
[0036] Since the further alternative parallelism adjusting section
allows that the joint surfaces of the semiconductor substrate and
the sealing substrate contact to each other, such that the one
substrate follows the other substrate, therefore the parallelism of
the substrates can be adequately adjusted even if flatness of each
of the substrate differs from the others. In addition, this
construction does not need the measuring instruments and the
analyzer for analyzing the measurement data. Therefore, the
parallelism adjustment can be performed less costly.
[0037] If the light-delayed curing adhesive is used as the
adhesive, the viscosity of the adhesive can be controlled inside
the device. Therefore, wettability of the adhesive to the spacer
can be improved in a small amount of time while the spacer is kept
from the adhesion of foreign matters.
BRIEF DESCRIPTION OF DRAWINGS
[0038] FIG. 1 is a perspective view of a solid state imaging device
manufactured by a device for joining substrates of the present
invention;
[0039] FIG. 2 is a partially sectional view of the solid state
imaging device;
[0040] FIG. 3 is a schematic view showing a structure of the device
for joining substrates;
[0041] FIG. 4 is a perspective view showing a wafer and a glass
substrate;
[0042] FIG. 5 is a schematic view showing a wafer supplying
section;
[0043] FIG. 6 is a schematic view showing a joined substrate
discharging section;
[0044] FIG. 7 is a partially sectional view showing a structure of
a joining station;
[0045] FIG. 8 is a top view of an underside joining unit;
[0046] FIG. 9 is a partially sectional view showing a state of the
joining station in joining position;
[0047] FIG. 10 is a partially sectional view showing a structure of
a primary portion of a plate supporting mechanism;
[0048] FIG. 11 is a partially sectional view showing a state of the
joining station when measuring a position of the substrate;
[0049] FIG. 12 is a schematic view showing arrangement of lights
and imaging cameras for parallelism measurement;
[0050] FIG. 13 is a partially sectional view showing a structure of
the light;
[0051] FIG. 14 is an explanatory view showing a positional relation
between the substrate and the imaging camera;
[0052] FIG. 15 is a graph showing a relation between a misalignment
amount of the substrates from a focal point of the imaging camera
and a measured value of distance between the wafer and the glass
substrate;
[0053] FIG. 16 is an explanatory view showing positional
relationship between a transcribing station and a film supplying
section;
[0054] FIG. 17 is a partially sectional view showing a structure of
the transcribing station;
[0055] FIG. 18 is a top view of the film supplying section;
[0056] FIGS. 19A, 19B are partially sectional views showing a
transcribing film on a transcribing unit;
[0057] FIG. 20 is a partially sectional view showing a state of the
transcribing station when joining the transcribing film and the
glass substrate;
[0058] FIGS. 21A-21D are explanatory views showing processes for
joining the wafer and the glass substrate;
[0059] FIG. 22 is a schematic view showing a structure of a peeling
station;
[0060] FIGS. 23A-23C are explanatory views showing stop positions
of a peeling roller;
[0061] FIG. 24 is a schematic view showing a state of the peeling
station in peeling the transcribing film;
[0062] FIG. 25 is a flow chart describing steps of operation of the
device for joining substrates;
[0063] FIG. 26 is a flow chart describing steps of parallelism
adjustment;
[0064] FIG. 27 is a top view showing an embodiment which uses
contour measurement devices for parallelism measurement;
[0065] FIG. 28 is a partially sectional view showing an embodiment
which uses laser displacement gauges for the parallelism
measurement;
[0066] FIG. 29A, 29B are partially sectional views showing an
embodiment which adjusts the parallelism such that the wafer and
the glass substrate contact to each other;
[0067] FIG. 30 is an explanatory view showing an embodiment which
has an illumination station between the transcribing station and
the film supplying section.
BEST MODE FOR CARRYING OUT THE INVENTION
[0068] As shown in FIG. 1 and FIG. 2, a solid state imaging device
2 of WLCSP type is constructed of an image sensor chip 3, a
frame-like spacer 4 which is adhered on the image sensor chip 3
with an adhesive 8, and a cover glass 5 which is adhered above the
spacer 4 so as to seal the inside of the spacer 4.
[0069] On the image sensor chip 3, an image sensor 6 including
plural pixels which generate electronic signal according to amount
of received light and a plurality of contact terminals 7 which
electrically connect to the image sensor 6, are provided. The image
sensor 6 is, for example, a CCD (Charge Coupled Device) on which
color filters and a micro lens are superimposed. The contact
terminals 7 are formed such that conductive material is printed,
for example, on the image sensor chip 3. In a similar way, the each
contact terminal 7 connects to the image sensor 6 by printed
wiring.
[0070] The spacer 4 is formed of inorganic material such as
silicon, and surrounds the image sensor 6. A transparent
.alpha.-ray shielding glass is used as the cover glass 5, so as to
prevent that photodiodes, which constitute the pixels of the CCD,
are destroyed by the .alpha.-ray. Since a space between the image
sensor 6 and the cover glass 5 is provided, the condensing
performance of the micro lens do not become worse.
[0071] The solid state imaging device 2 is embedded in a small
electronic apparatus (such as a digital camera, a mobile phone and
the like), together with a taking lens for focusing object images
on the image sensor 6, a memory for storing the image data
generated according to the image taking, a control circuit for
controlling the solid state imaging device 2, and so on. Since the
solid state imaging device 2 of WLCSP type has the size and the
thickness nearly equal to the bare chip, the apparatus
incorporating the solid state imaging device 2 can be
downsized.
[0072] As shown in FIG. 3, a device for joining substrates 11 which
is used for manufacturing the solid state imaging device 2 is
provided in a clean booth 12 sealed from the outside. Note that,
for illustrating purpose, two directions which are parallel to a
sheet of FIG. 3 and are at right angles to each other are
determined as an X-axis direction and a Y-axis direction, and a
direction perpendicular to a face formed by the X-axis and the
Y-axis is determined as a Z-axis direction.
[0073] The clean booth 12 connects to an air conditioner 13 which
has a HEPA filter or the like, therefore clean air is down-flowing
in the clean booth 12. Dusts are gathered around a floor surface of
the clean booth 12 by the clean air, aspirated by a blower 14, and
exhausted to the outside of the clean booth 12. The air conditioner
13 and the blower 14 are controlled by a control computer 15 which
controls the device for joining substrates 11.
[0074] Note that sources of foreign matters, such as moving parts
of devices in the clean booth 12, can be covered by covers and so
on, for making the inside of the clean booth 12 more cleaner. In
addition, for preventing reflection of the down-flowing of the
clean air, the floor surface of the clean booth 12 and bases of the
devices inside the clean booth 12 may be formed of punching members
or the like.
[0075] On a side wall of the clean booth 12, openings 17-19 for
supplying and discharging work in and from the device for joining
substrates 11 in the clean booth 12, and doors 20-22 for opening
and closing the openings 17-19 are provided. Note that for
preventing air including the foreign matters flowing into the clean
booth 12 when the doors 20-22 are opened, the air conditioner 13
and the blower 14 keep barometric pressure inside the clean booth
12 higher than that of outside the clean booth 12.
[0076] Wafers 25 which are semiconductor substrates are supplied
into the clean booth 12 through the opening 17. Behind the opening
17, a wafer supplying section 26 for supplying the wafers 25 into
the device for joining substrates 11 is provided. As shown in FIG.
4, the wafer 25 is, for example, eight inches in size. On one
surface of the wafer 25, the plurality of the image sensors 6 and
the plurality of the contact terminals 7 which correspond to the
respective image sensors 6 are formed by a semiconductor wafer
process. The image sensor chip 3 of the solid state imaging device
2 is formed by dividing the wafer 25 into individual image sensor
6.
[0077] As shown in FIG. 5, the wafer 25 is contained in a known
open cassette 28 such that the surface of the wafer on which the
image sensor 6 and so on are formed is directed upward, and is set
on a base 30 provided in the wafer supplying section 26. On the
open cassette 28, plural container slot 29 for containing the wafer
25 one by one are provided along the vertical direction. On a
support plate 29a of each of the container slot 29, a cutout 29b,
in which an adsorption hand 49 of a robot (described later) is
inserted when the robot holds the bottom surface of the wafer 25 to
lift up, is formed.
[0078] Glass substrates 33 which are sealing substrate are supplied
into the clean booth 12 through the opening 18. Behind the opening
18, a glass substrate supplying section 34 for supplying the glass
substrates 33 into the device for joining substrates 11. As shown
FIG. 4, the glass substrate 33 is formed such that the frame-like
spacers 4 is formed on one surface of the transparent .alpha.-ray
shielding glass which has the same size and shape as the wafer 25.
The cover glass 5 of the solid state imaging device 2 is formed
such that the glass substrate 33 is joined to the wafer 25 such
that the each spacer 4 surrounds the each image sensor 6 on the
wafer 25 and is cut with the wafer 25. The glass substrate 33 is
contained in an open cassette 35 similar to the open cassette 28,
such that the surface of the substrate on which the spacers 4 are
formed is directed upward, and is set on a base 36.
[0079] The spacer 4 is formed on the glass substrate 33 in such a
way as described next. First, on the glass substrate 33, inorganic
materials such as silicon are superimposed to form an inorganic
material coat by spin coating or CVD. Then the plurality of the
spacer 4 is formed from the inorganic material coat by
photolithography, development, etching or so on. Note that the
inorganic material coat may be formed by joining the glass
substrate 33 and a silicon wafer together.
[0080] The wafer 25 and the glass substrate 33 which are joined
together at the device for joining substrates 11 in the clean booth
12 (hereinafter joined substrate 39) are discharged outside the
clean booth 12 through the opening 19. Behind the opening 19, a
joined substrate discharging section 40 is provided. In the joined
substrate discharging section 40, a substrate case 41 for
containing one of the joined substrate 39 is disposed. The
substrate case 41 is, for example, a tray formed of plastic.
[0081] As shown in FIG. 6, in the joined substrate discharging
section 40, a case supplying device 42 for automatically supplying
the plural substrate case 41 is provided. The case supplying device
42 is constituted of a container 42a for stacking and containing
the plural substrate case 41, a support plate 42b on which the
plural substrate case 41 are supported, and an actuator 43 for
moving the support plate 42b up and down. The actuator 43 is
controlled by the control computer 15.
[0082] When the joined substrate 39 is contained in the uppermost
substrate case 41 of the case supplying device 42, the substrate
case 41 is discharged from the opening 19 to outside the clean
booth 12 to be conveyed to next manufacturing line. The case
supplying device 42 drives the actuator 43 to push up the stacked
plural substrate case 41 such that the uppermost substrate case 41
is positioned behind the opening 19.
[0083] Note that in this embodiment, although the open cassettes
28, 35 as the carriers of the wafer 25 and the glass substrate 33,
known FOUP (Front Opening Unified Pod) can be used instead of the
open cassette. When the FOUP is used, load ports may be provided on
the side wall of the clean booth 12, for feeding the wafer 25 and
the glass substrate 33 from outside of the clean booth 12.
[0084] Behind the wafer and glass substrate supplying sections 26
and 34, and the joined substrate discharging section 40 in the
clean booth 12, a single axis robot 46 and a five axis robot 47
which comprise a substrate conveying mechanism are provided. The
single axis robot 46 moves the five axis robot 47 in the Y-axis
direction and stops the movement at predetermined positions. Each
stop position of the five axis robot 47 is a wafer receiving
position where the wafer supplying section 26 faces, a glass
substrate receiving position where the glass substrate supplying
section 34 faces, a joined substrate discharging position where the
joined substrate discharging section 40 faces, an alignment
position where an alignment station 53 faces, and a joining
position where a joining station 57 faces. Note that as described
later in detail, the alignment station 53 is for tentatively
positioning of the wafer 25 and the glass substrate 33, and the
joining station 57 is for joining the wafer 25 and the glass
substrate 33.
[0085] As shown in FIG. 5 and FIG. 6, the five axis robot 47,
so-called a horizontal articulated robot or a scalar robot, is
well-known used for handling the wafer and the like in
manufacturing the semiconductor devices. The five axis robot 47
comprises a body 47a supported by the single axis robot 46, a robot
arm 48 attached on an upper portion of the body 47a, and a suction
hand 49 attached on an end of the robot arm 48. The suction hand 49
has a thin plate-like shape, and scoops and holds the wafer 25 and
the glass substrate 33 by vacuum sucking.
[0086] A first axis 50a of the five axis robot 47 is provided in
the body 47a, for moving whole of the robot arm 48 up and down (in
the Z-axis direction). The robot arm 48 comprises three arms
48a-48c, second to fourth axes 50b-50d for moving the suction hand
49 in horizontal direction by bending and stretching the arms
48a-48c, and a fifth axis 50e for inverting the suction hand 49.
The single axis robot 46 and the five axis robot 47 are controlled
by the control computer 15.
[0087] At first, the five axis robot 47 is moved to the glass
substrate receiving position by the single axis robot 46, and picks
up the single glass substrate 33 from the open cassette 35. Next,
the five axis robot 47 is moved to the alignment position, and sets
the glass substrate 33 on the alignment station 53. Note that
because the glass substrate supplying section 34 and the alignment
station 53 are faced across the single axis robot 46, in practice
only the second axis 50b of the robot arm 48 is rotated to face the
alignment position. After finishing the operation in the alignment
station 53, the five axis robot 47 receives the glass substrate 33
from the alignment station 53, and is moved to the joining station
57 by the single axis robot 46, to set the glass substrate 33 on
the joining station 57.
[0088] After setting the glass substrate 33 on the joining station
57, the five axis robot 47 is moved to the wafer receiving
position, and takes the single wafer 25 from the open cassette 28.
Then the wafer 25 is set on the alignment station 53. After
finishing the operation in the alignment station 53, the five axis
robot 47 receives the wafer 25 from the alignment station 53, and
set the wafer 25 on the joining station 57.
[0089] After the wafer 25 and the glass substrate 33 are joined by
the device for joining substrates 11, the five axis robot 47
receives the joined substrate 39 from the joining station 57. Then
the single axis robot 46 moves the five axis robot 47 to the joined
substrate discharging position, where the joined substrate 39 is
contained in the substrate case 41 of the joined substrate
discharging section 40.
[0090] As the alignment station 53, known alignment device for
wafer is used for tentatively positioning the wafer 25 and the
glass substrate 33 in the X-axis direction, the Y-axis direction,
and the rotational direction. The alignment station 53 is
controlled by the control computer 15. By the five axis robot 47,
the wafer 25 or the glass substrate 33 from the wafer supplying
section 26 or the glass substrate supplying section 34 is set on a
pad 54 of the alignment station 53 without being inverted.
[0091] In the alignment station 53, a motor rotates the pad 54, and
an optical sensor detects the orientation flat 25a or 33a or
notches of the wafer 25 or the glass substrate 33. Then the
direction of the wafer 25 or the glass substrate 33 is aligned such
that the rotational position of the pad 54 is controlled according
to the detected position of the orientation flat 25a or 33a or
notches.
[0092] In addition, the pad 54 is supported by a known XY table for
tentatively positioning the wafer 25 and the glass substrate 33 in
the X-axis direction and the Y-axis direction by moving the pad 54.
The position accuracy of the wafer 25 and the glass substrate 33 in
the alignment station 53 is 0.6 mm in the X-axis direction and the
Y-axis direction, and .+-.0.2.degree. in the rotational
direction.
[0093] As shown in FIG. 7 and FIG. 8, the joining station 57
comprises an underside joining unit 61 having a wafer support plate
60 for holding the wafer 25 or the glass substrate 33 on its top
surface, and an topside joining unit 63 having a glass support
plate 62 for holding the glass substrate 33 at a position above the
wafer support plate 60. As shown in FIG. 9, when joining the wafer
25 and the glass substrate 33, the underside joining unit 61 moves
upward so as to press the wafer 25 against the glass substrate
33.
[0094] The wafer support plate 60 is formed of a ceramic plate
having planarity, for example, and holds the glass substrate 33 and
the wafer 25, stuck sequentially by the five axis robot 47, by the
vacuum sucking. The glass support plate 62 receives and holds the
glass substrate 33 from the wafer support plate 60 such that the
wafer support plate 60 can receive the wafer 25. Note that the
wafer support plate 60 may be formed of a metal plate such as a
stainless plate, if the plate has high planarity.
[0095] The underside joining unit 61 comprises first to third
lifting actuators 66-68 for adjusting inclination of the wafer 25
and pressing the wafer 25 against the glass substrate 33, first to
third pressure control cylinders 69-71 for controlling the pressing
forces of the first to third lifting actuators 66-68 when joining
the wafer 25 and the glass substrate 33, an XY.theta. table 72 for
moving the wafer support plate 60 in the X-axis direction, Y-axis
direction and the rotational direction, and first to third plate
supporting mechanism 73-75. The first to third lifting actuators
66-68 are positioned equiangularly at intervals of 120.degree.
around the center of the wafer support plate 60, and the first to
third plate supporting mechanism 73-75 are positioned respectively
on respective extension lines from the center of the wafer support
plate 60 toward the respective lifting actuators 66-68.
[0096] The first lifting actuator 66 has a shaft 77a moving in the
Z-axis direction by rotation of a motor 77. To the shaft 77a, the
first pressure control cylinder 69 is attached. On top of a shaft
69a of the first pressure control cylinder 69, a hemispherical
plate supporter 69b is provided for supporting a bottom surface 78a
of a swingable plate 78 on which the wafer support plate 60 and the
XY.theta. table 72 are held, by point contact.
[0097] The first pressure control cylinder 69 contracts such that
an excess pressure can escape when the pressure of the first
lifting actuator 66 in pressing the wafer 25 against the glass
substrate 33 exceeds a predetermined value (for example 7 kgf).
Note that the second and third lifting actuators 67, 68 have the
structure same as the first lifting actuator 66, and the second and
third pressure control cylinders 70, 71, which have the structure
same as the first pressure control cylinder 69, are respectively
attached to the second and third lifting actuators 67, 68.
[0098] Because the first to third lifting actuators 66-68 are
positioned equiangularly at intervals of 120.degree. around the
center of the wafer support plate 60, the inclination of the wafer
25 can be adjusted in a balanced manner. In addition, because the
first to third lifting actuators 66-68 are positioned at positions
facing the edge of the wafer 25 set on the wafer support plate 60,
the movement of the lifting actuators 66-68 can be effectively
transmitted to the wafer 25. Therefore, short stroke actuators can
be used as the lifting actuators 66-68.
[0099] The XY.theta. table 72 for moving the wafer support plate 60
in the X-axis direction, the Y-axis direction, and the rotational
direction, comprises known ball screws, ball screw nuts, guide
shafts, slide bearings and so on. The XY.theta. table 72 adjusts
the positions of the wafer 25 and the glass substrate 33 by moving
the wafer support plate 60.
[0100] As shown in FIG. 10 in close-up, the first plate supporting
mechanism 73 comprises a guide shaft 81 provided on a frame 61a of
the underside joining unit 61, a supporting arm 82 slidably
inserted to the guide shaft 81, a spherical shaft 83 provided on
the swingable plate 78, a spherical bearing 82a provided in the
supporting arm 82 to contact the spherical shaft 83 with allowing
rotation of the spherical shaft 83, and a spring 84 for biasing the
supporting arm 82 downward. The center of the spherical shaft 83 is
in a position coplanar with a joint surface of the wafer 25
positioned on the wafer support plate 60. Note that the second and
third plate supporting mechanisms 74, 75 have the same structure as
the first plate supporting mechanism 73. Therefore the detailed
descriptions are omitted.
[0101] A vacuum pump 80, for vacuum sucking the wafer 25 or the
glass substrate 33 through the wafer support plate 60, is provided
among the first to third lifting actuators 66-68. The first to
third lifting actuators 66-68, the XY.theta. table 72, and the
vacuum pump 80 are controlled by the control computer 15. In the
frame 61a, slide bearings 79 for guiding the shafts 69a, 77a are
embedded.
[0102] When adjusting parallelism between the wafer 25 and the
glass substrate 33 by the underside joining unit 61, the lifting
actuators 66-68 are respectively driven according to result of
parallelism measurement of the wafer 25 and the glass substrate 33,
for moving the shaft 77a in vertical direction to adjust the height
of the plate supporters 69b. When inclination of the swingable
plate 78 according to the movement of the plate supporters 69b, the
supporting arms 82 of the plate supporting mechanisms 73-75 push
the spherical bearing 82a to the spherical shaft 83 by biasing of
the spring 84. Accordingly, the swingable plate 78 swings from the
spherical shaft 83, on the joint surface of the wafer 25, so as to
adjust the inclination of the wafer 25. Therefore, misalignment in
the horizontal direction of the wafer 25 in the parallelism
adjustment is minimized.
[0103] In addition, when joining the wafer 25 and the glass
substrate 33, the first to third lifting actuators 66-68 are driven
in synchronization. The respective plate supporters 69b push the
undersurface of the swingable plate 78 to move the wafer 25 upward
to a joining position. Accordingly, the wafer 25 is pressed to the
glass substrate 33 with keeping the inclination determined at the
parallelism adjustment.
[0104] When joining the wafer 25 and the glass substrate 33, the
wafer 25 follows the inclination of the held glass substrate 33,
then the swingable plate 78 swings according to the rotation of the
spherical shafts 83 of the respective plate supporting mechanisms
73-75. Because the swing of the swingable plate 78 is performed on
the joint surface of the wafer 25, therefore misalignment of the
joining position between the wafer 25 and the glass substrate 33 is
minimized.
[0105] When the wafer 25 is pressed against the glass substrate 33
by the first to third lifting actuators 66-68, if the pressure of
one or more of the lifting actuators 66-68 exceeds the
predetermined value (for example 7 kgf by one lifting actuator),
the one or more of pressure control cylinders 69-71 attached to the
lifting actuator which exceeds the predetermined pressure value,
contract such that the excess pressure escapes. Accordingly, the
wafer 25 and the glass substrate 33 are prevented from being
locally pushed too hard, which prevents problems of running off the
adhesive 8 from under the each spacer 4 and breaking the wafer 25
and the glass substrate 33.
[0106] The topside joining unit 63 comprises the glass support
plate 62, a plate supporting member 86 which has a crank-shaped
cross section and supports the glass support plate 62, and a vacuum
pump 87 for vacuum sucking the glass substrate 33 through the glass
support plate 62. The glass support plate 62 is made of for example
a circular disk of glass plate which has planarity and high load
bearing capacity. The plate supporting member 86 is attached to a
single axis robot 93 for the glass substrate which moves the plate
supporting member 86 along the joining station 57, a transcribing
station 91 and a peeling station 92 (see FIG. 3).
[0107] The glass support plate 62 is moved between the joining
station 57 and the peeling station 92 and stopped for operation of
each station, with holding the glass substrate 33. Accordingly, the
glass substrate 33 is not need to be transferred between the
joining station 57 and the transcribing station 91. Therefore,
mechanisms and operations for transferring the glass substrate 33
can be cut. In addition, misalignment of the glass substrate 33
caused by transferring can be prevented.
[0108] The wafer 25 and the glass substrate 33 are lapped and
joined with being held by the wafer support plate 60 and the glass
support plate 62. Accordingly, the glass substrate 33 has to be
held by the glass support plate 62 such that the surface on which
the spacer 4 is provided faces the wafer 25 held on the wafer
support plate 60. In other words, the glass substrate 33 has to be
held such that the spacer 4 is directed downward. However, the
glass substrate 33 is contained in the open cassette 35 with the
spacer 4 being directed upward, and is transferred onto the
alignment station 53 with keeping its direction. Accordingly, the
glass substrate 33 is inversed with the suction hand 49 by rotating
the fifth axis of the robot arm 48 of the five axis robot 47 (shown
in FIG. 5), when the glass substrate 33 is transferred to the
joining station 57 from the alignment station 53.
[0109] As shown in FIG. 11, in a position above the joining station
57 where the topside joining unit 63 is not interfered, a substrate
imaging camera 96, which images the glass substrate 33 or the wafer
25 held on the wafer support plate 60 when the topside joining unit
63 is not positioned above the underside joining unit 61, is
provided. The substrate imaging camera 96 is operated for
definitely positioning the glass substrate 33 or the wafer 25.
[0110] The image data of the glass substrate 33 or the wafer 25
taken by the substrate imaging camera 96 is inputted to an image
processor 98. The image processor 98 calculates a position
coordinate of the glass substrate 33 or the wafer 25 such that for
example the inputted image data is processed to become a binary
data. The position coordinate calculated by the image processor 98
is inputted to the control computer 15 for being compared with a
prerecorded reference position. Then the XY.theta. table 72 is
driven such that the glass substrate 33 or the wafer 25 is
positioned at the reference position. Note that the image processed
by the image processor 98 can be monitored by a monitor 99 provided
outside of the clean booth 12.
[0111] Note that the substrate imaging camera 96 has two kinds of
taking lenses, one has low magnification and the other has high
magnification. When the lens of low magnification is used, whole of
the glass substrate 33 or the wafer 25 is imaged, such that the
position thereof is measured based on their outline. When the lens
of high magnification is used, alignment marks provided on the
wafer 25 and the glass substrate 33, the spacer 4, details of the
image sensor 6 and so on are imaged so as to measure the position
coordinate of the wafer 25 and the glass substrate 33.
[0112] As shown in FIG. 3, a substrate imaging camera 100 is
provided between the joining station 57 and the transcribing
station 91, for imaging the glass substrate 33 held by the glass
support plate 62 before joining the glass substrate 33 and the
wafer 25. When the substrate imaging camera 100 images the glass
substrate 33, the topside joining unit 63 is positioned between the
joining station 57 and the transcribing station 91, at a position
where the substrate imaging camera 100 faces.
[0113] The image data of the glass substrate 33 taken by the
substrate imaging camera 100 is inputted into the image processor
98 as same as the image data taken by the substrate imaging camera
96, for measurement of position of the glass substrate 33 on the
glass support plate 62. Note that the glass support plate 62 has
not a mechanism for adjusting position of the glass substrate 33.
Therefore, the result of the position measurement of the glass
substrate 33 performed just before the joining is used for
adjusting the position of the wafer 25 on the wafer support plate
60.
[0114] Note that the position accuracy of the wafer 25 and the
glass substrate 33 adjusted by the imaging cameras 96, 100 and the
XY.theta. table 72 is, for example, .+-.0.005 mm in the X-axis
direction and the Y-axis direction, and .+-.0.0002.degree. in the
rotational direction.
[0115] As shown in FIG. 7, FIG. 8 and FIG. 12, on an outer
peripheral portion of the upper surface of the wafer support plate
60, first to third clearance imaging cameras 102-104 for measuring
parallelism of the joint surfaces of the wafer 25 and the glass
substrate 33, and first to third lights 105-107 faced respectively
to the first to third clearance imaging cameras 102-104 are
arranged equiangularly. In this embodiment, the joint surface of
the wafer 25 and the joint surface of the glass substrate 33 are
arranged so as to make predetermined clearance S (for example S=1
mm), and the clearance between the joint surfaces are illuminated
by the first to third lights 105-107 to be imaged by the first to
third clearance imaging cameras 102-104. Then the parallelism is
measured by calculating the length of the clearance between the
wafer 25 and the glass substrate 33 obtained by the image data.
[0116] The first to third lights 105-107 as transmission
illuminating devices, are turned on by light controllers 108-110
controlled by the control computer 15. As shown in FIG. 13, the
light 105 has a LED 105a as a light source. Lights emitted from the
LED 105a are condensed by a condenser lens 105b, and restricted by
a slit 105d formed on a case 105c of the first light 105, so as to
be approximately parallel light which has a converging angle
.theta.2 of 1.degree. or less, for example 0.2.degree.. When
imaging the area between the wafer 25 and the glass substrate 33,
there may be a problem of reflection noises which occur by the
light emitted from the first light 105 being reflected by the joint
surfaces of the substrates to enter to the imaging cameras.
However, in this embodiment, the reflection noises are reduced such
that the converging angle .theta.2 of the first light 105 is
narrowed for reducing the reflection at the joint surfaces. Note
that the second and third lights 106, 107 have a structure same as
the first light 105, therefore detailed descriptions are
omitted.
[0117] Focus positions of the transmissions from the lights 105-107
are on ends of the substrates where the transmission is emitted
between the wafer 25 and the glass substrate 33, for example points
P1-P3 shown in FIG. 12. These focus positions P1-P3 are positions
which are imaged by the first to third clearance imaging camera
102-104.
[0118] The first clearance imaging camera 102 has a taking lens
102a and a solid state imaging device 102b such as a CCD, which
images object lights entered through the taking lens 102a, so as to
image the point P1 illuminated by the light 105. As the taking lens
102a, a telecentric lens in which only the parallel lights can
enter. Accordingly, the reflection lights from the joint surfaces
of the wafer 25 and the glass substrate 33 can hardly enter to the
first clearance imaging camera 102. Therefore, the reflection noise
can hardly affect the imaging. Note that the second and third
clearance imaging cameras 103, 104 have a structure same as the
first clearance imaging camera 102, therefore detailed descriptions
are omitted.
[0119] A graph in FIG. 15 shows a relation between a distance
between the point P1 and a focal point F1 of the first clearance
imaging camera 102, and a measured value of the distance between
the wafer 25 and the glass substrate 33. The measurement is
performed at conditions that a distance W between the end of the
taking Lens 102a and the focal point F1 is 65 mm, a focal depth of
the taking lens 102a is 100 .mu.m, a height t of the slit 105d is
1.2 mm and the clearance S between the wafer 25 and the glass
substrate 33 is 0.8 mm.
[0120] The graph shows that when the converging angle of the first
light 105 is narrowed and the telecentric lens is used as the
taking lens 102a, difference of the measured value is reached only
2 .mu.m even if the distance between the point P1 and the focal
point F1 becomes few millimeters, for example over 1 mm (ten times
larger than the depth of field). This is because the first
clearance imaging camera 102 is hardly affected by the reflection
noises even if the point P1 is apart from the focal point F1.
Therefore, positioning of the wafer 25 and the glass substrate 33
against the first to third clearance imaging cameras 102-104 can be
simplified.
[0121] The image data generated by the first to third clearance
imaging cameras 102-104 is inputted into the image processor 98.
The image processor 98 processes the image data to a binary data,
and outputs the binary data to the control computer 15. The control
computer 15 calculates a clearance L1 between the wafer 25 and the
glass substrate 33 at the point P1, a clearance L2 at the point P2,
and a clearance L3 at the point P3 (see FIG. 12).
[0122] The control computer 15 drives the first to third lifting
actuators 66-68 based on the measured clearances L1-L3, so as to
equalize the clearances at the points P1-P3, which are on the ends
of the wafer 25 and the glass substrate 33. Accordingly, because
the joint surfaces of the wafer 25 and the glass substrate 33
become parallel, it is prevented that the joining positions of the
substrates are misaligned and the adhesive 8 is run off from the
substrates in the joining. Note that the accuracy of adjusting the
clearance between the wafer 25 and the glass substrate 33 by the
first to third lifting actuator 66-68 is, for example, .+-.0.001 mm
per the one point.
[0123] Beside the joining station 57, the transcribing station 91
for transcribing the adhesive on the spacers 4 on the glass
substrate 33, a film supplying section 113 for supplying a
transcribing film 112 which is pre-coated by the adhesive 8 to the
transcribing station 91, and the peeling station 92 for peeling the
transcribing film 112 from the glass substrate 33 are arranged.
[0124] In the transcribing station 91, the transcribing film 112
and the glass substrate 33 are laminated and pressurized. Then in
the peeling station 92, the transcribing film 112 is peeled off
from the glass substrate 33, such that the layer of the adhesive 8
is formed on the spacer 4 by transcribing. According to the
transcribing, the adhesive 8 can be coated on the spacer 4 with
thin and constant thickness. Therefore, it is prevented that the
excessive adhesive 8 runs onto the image sensor 6 or defective
joining occurs. In addition, a yield ratio of the product can be
increased because the adhesive 8 is not dripped onto the glass
substrate 33 in coating.
[0125] As shown in FIG. 16, in the transcribing station 91, a
transcribing unit 114, which can move between a film receiving
position for receiving the transcribing film 112 from the film
supplying section 113, and a transcribing standby position where
the transcribing film 112 faces the glass substrate 33 held by the
topside joining unit 63 at the transcribing station 91, is
provided. The transcribing unit 114 is moved by a single axis robot
115 for transcribing provided between the transcribing station 91
and the film supplying section 113.
[0126] As shown in FIG. 17, in the transcribing unit 114, a plate
for transcribing 116 which holds the transcribing film 112 received
from the film supplying section 113 by vacuum sucking, and sticks
the transcribing film 112 to the glass substrate 33 held by the
glass support plate 62, is provided. As the plate for transcribing
116, a plate-like cushion is used for increasing degree of adhesion
between the transcribing film 112 and the glass substrate 33. In
addition, the plate for transcribing 116 is set on a backing board
117 formed of a metal plate such as stainless which has planarity,
so as to have planarity.
[0127] For the cushion used for the plate for transcribing 116, a
material for example sponge rubber which has low degree of hardness
and a low-dusting skin surface or the like is preferable. In
particular, for example silicon sponge rubber or the like which has
hardness of ASKER-C 20-40 (SRIS (The Society of Rubber Industry,
Japan Standard)) is preferable.
[0128] In the transcribing unit 114, for example three transferring
actuators 120 for transferring the transcribing film 112 from the
film supplying section 113 to the plate for transcribing 116, and a
pressurization actuator 121 for moving the plate for transcribing
116 up and down and overlapping and pressurizing the glass
substrate 33 held by the glass support plate 62 and the
transcribing film 112, are provided.
[0129] The three transferring actuators 120 are incorporated under
the backing board 117, and arranged equiangularly around the center
of the plate for transcribing 116. Each of the transferring
actuators 120 projects a plunger 120a upward when the transcribing
unit 114 is moved to the film receiving position, so as to handle
the transcribing film 112 in the film supplying section 113 by
uplifting the transcribing film 112 with holding undersurface
thereof. The transferring actuators 120 are controlled by the
control computer 15. Note that a vacuum pump 125, for vacuum
sucking the transcribing film 112 to hold it on the plate for
transcribing 116, is provided among the three actuators 120.
[0130] On the side wall of the clean booth 12, an opening 134 is
formed at a position where the film supplying section 113 faces.
And a door 135 is provided for opening and closing the opening 134.
In the film supplying section 113, a holder 138 on which a film
case having a shape like a tray which contains the transcribing
film 112 is provided. As shown in FIG. 18, in the holder 138 and
the film case 137, three slits 138a, 137a are respectively formed
for allowing the plunger 120a of the transferring actuators 120
being inserted in there, when transferring the transcribing film
112 from the film case 137 to the plate for transcribing 116.
[0131] As shown in FIG. 19A, when the transcribing unit 114 is
moved under the holder 138 of the film supplying section 113 by the
single axis robot 115 for transcribing, each of the plunger 120a of
the three transferring actuators 120 is projected upward, so as to
enter the slits 137a, 138a which are respectively provided by three
and lift up the transcribing film 112. Next, as shown in FIG. 19B,
the transcribing unit 114 is moved from under the holder 138 and
then temporary stopped by the single axis robot 115 for
transcribing. At this time, each of the plungers 120a of the three
transferring actuators 120 is moved downward so as to set the
transcribing film 112 on the plate for transcribing 116, as shown
in FIG. 17.
[0132] Note that because the transferring actuator 120 has a
plunger which is thin, a large hole for plunger is not required in
the plate for transcribing 116. Therefore, the pressurization of
the transcribing film 112 and the glass substrate 33 by the plate
for transcribing 116 is prevented from adverse influence of the
hole.
[0133] As shown in FIG. 20, the pressurization actuator 121 moves a
plunger 121a upward so as to press a frame 128 on which the three
transferring actuators 120 are attached. Accordingly, the plate for
transcribing 116 is moved upward to a transferring position and
pushes the transcribing film 112 to the glass substrate 33 held by
the glass support plate 62 for transferring the adhesive 8 to the
each spacer 4. Note that pressure of the plate for transcribing 116
in pressurization of the glass substrate 33 and the transcribing
film 112 is, for example, 20 kgf.
[0134] Around the pressurization actuator 121, plural guide shafts
130 for guiding movement of the frame 128, and slide bearings 131
attached to the frame 128 for guiding slide of the guide shaft 130,
are provided. The pressurization actuator 121 is controlled by the
control computer 15.
[0135] As shown in FIG. 21A, the transcribing film 112 is a thin
film evenly formed from, for example, polyethylene terephthalate
(PET), which has elasticity for allowing to be bended and a size
larger than a diameter of the glass substrate 33. The adhesive 8 is
coated on the transcribing film 112 by for example a bar coater, a
spin coater or a blade coater. The transcribing film 112 on which
the adhesive 8 is coated is contained in the film case 137. Note
that if static electricity is caused on the transcribing film 112,
the static electricity adversely affects handling of the
transcribing film 112. Therefore, antistatic treatment is applied
on the transcribing film 112.
[0136] As general characteristic of the adhesive, it is known that
wettability for inorganic material such as silicon becomes worse
when its viscosity is low, and the wettability becomes improved
when its viscosity is high. However, if the adhesive having high
viscosity is used, it becomes difficult to control coating
thickness of the adhesive on the transcribing film 112. Therefore,
in this embodiment, normal temperature curable adhesive is used as
the adhesive 8, for increasing its viscosity by leaving the
transcribing film 112 in the film case 137 for predetermined
period. Hereinafter, the viscosity controlling with time is called
as time process.
[0137] Because the viscosity of the adhesive 8 becomes high when
the adhesive 8 is transcribed on the spacer 4, the adhesive 8
becomes harder to flow out. Therefore, the transcribing film 112
and the glass substrate 33 on which the adhesive 8 is transcribed
become easier to be handled. In addition, the adhesive 8 running
off from under the spacer 4 can be reduced when the pressurization
of the glass substrate 33 and the wafer 25. Note that when
hydrophilic adhesive is used, the spacer 4 can be applied surface
reforming by irradiation of plasma or ultraviolet lay. By the
surface reforming process, the wettability of the adhesive for the
spacer 4 formed from silicon can be improved.
[0138] As shown in FIG. 22, the peeling station 92 comprises a base
145 standing along vertical direction, a feeding reel 146 and a
winding reel 147 which are rotatably held by the base 145, a
peeling actuator 149 attached to the base 145 for moving a plunger
148 in the X-axis direction, and a peeling unit 150 attached to the
plunger 148.
[0139] In the feeding reel 146, an unused adhesive tape 153, wound
such that an adhesive surface 153a is directed inside, is set. A
long adhesive tape 153 drawn from the feeding reel 146 is hanged on
a guide roller 154 provided on the base 145, the peeling unit 150
and a guide roller 155, and connected to the winding reel 146. The
winding reel 146 is rotated in counterclockwise direction by a
motor (not shown) so as to wind the used adhesive tape 153 and the
transcribing film 112 peeled off from the glass substrate 33 by
adhering to the adhesive tape 153.
[0140] The adhesive tape 153 between the guide roller 154 and the
peeling unit 150 adheres to the transcribing film 112 such that the
adhesive surface 153a faces the glass support plate 62 which holds
the glass substrate 33 on which the transcribing film 112 is
adhered. The width of the adhesive tape 153 is, for example, 75
mm.
[0141] The peeling unit 150 comprises a base plate 158 attached to
top of the plunger 148, a swing arm 159 swingably attached to the
base plate 158, a peeling roller 160 rotatably attached to top of
the swing arm 159 for hanging the adhesive tape 153, an actuator
for swing 161 having a slot 161a for linking to a pin 159a formed
in one end of the swing arm 159, and a guide roller for guiding the
adhesive tape 153.
[0142] The actuator for swing 161 of the peeling unit 150 swings
the swing arm 159 by movement of a plunger 161b in which the slot
161a is formed, so as to move the peeling roller 160 attached on
the top of the swing arm 159 among a retract position, an adhesion
position and a peeling position. The peeling roller 160 is moved to
the retract position when the glass support plate 62 is moved to
the peeling station 92.
[0143] As shown in FIG. 23A, the retract position of the peeling
roller 160 is apart from the transcribing film 112. When the
peeling roller 160 is at the retract position, the adhesive tape
153 hanged between the peeling roller 160 and the guide roller 154
is also apart from the transcribing film 112. Accordingly, it is
prevented that the adhesive tape 153 contacts to the transcribing
film 112 when the glass support plate 62 is moved to the peeling
station 92.
[0144] As shown in FIG. 23B, the peeling roller 160 is moved to the
adhesion position for attaching the adhesive tape 153 to the
transcribing film 112. When the peeling roller 160 is moved to the
adhesion position, the adhesive surface 153a of the adhesive tape
153 hanged on the peeling roller 160 is moved to a position higher
than undersurface of the transcribing film 112. Therefore, the
adhesive tape 153 hanged between the peeling roller 160 and the
guide roller 154 is certainly adhered on the transcribing film
112.
[0145] As shown in FIG. 23C, the peeling roller 160 is moved to the
peeling position for peeling the transcribing film 112 from the
glass substrate 33. When the peeling roller 160 is set to the
peeling position, a clearance L5 is formed between the adhesive
surface 153a of the adhesive tape 153 hanged on the peeling roller
160 and the undersurface of the transcribing film 112. Accordingly,
the peeling roller 160 does not press the transcribing film 112
when the peeling roller 160 peels off the transcribing film 112
with moving rightward in the figure. Therefore, it is prevented
that the adhesive 8 runs off.
[0146] As shown in FIG. 24, the peeling actuator 149 is pulling the
plunger 148 back in a housing 149a at a constant speed when the
peeling roller 160 is set at the peeling position from the adhesion
position. At the same time, the winding reel 146 is rotated in the
counterclockwise direction. Accordingly, the transcribing film 112
adhered to the glass substrate 33 is rolled up to be peeled off
from top end thereof by the adhesive tape 153. The used adhesive
tape 153 and the peeled transcribing film 112 can be ejected from
an opening 167 by opening a door 166 on the side wall of the clean
booth 12.
[0147] A curvature of the transcribing film 112 is kept constant
while the peeling operation because the curvature is determined by
a radius R1 of the peeling roller 160. In addition, a peeling angle
.theta.1 of the transcribing film 112 against the joint surface of
the glass substrate 33 is determined by relative positions of the
peeling roller 160 and a guide roller 162, which do not vary
because these members are moved together. Accordingly, peeling
condition between the transcribing film 112 and the glass substrate
33 is kept constant. Therefore, it is prevented that a membrane of
the adhesive 8 are generated between the glass substrate 33 and the
transcribing film 112, and the membrane bursts to mess the glass
substrate 33.
[0148] Note that it is preferable that the clearance L5 is, for
example, below 0.1 mm. If the clearance becomes larger, the
curvature of the transcribing film 112 becomes substantially larger
than the radius of the peeling roller 160 while the peeling
operation. Accordingly, the clearance L5 is preferably determined
as a value not to generate the membrane of the adhesive 8, with
considering the radius of the peeling roller 160.
[0149] In addition, the curvature of the transcribing film 112 in
the peeling operation can be adjusted by changing the peeling
roller 160 for another one which has different diameter. When
changing the peeling roller 160, the retract position, the adhesion
position and the peeling position of the peeling roller 160 are
also need to be adjusted. However, these positions can be easily
adjusted by controlling the projection length of the plunger 161b
of the actuator for swing 161.
[0150] Next, an operation of the above embodiment is explained with
referring to a flow chart of FIG. 25. The single axis robot 46
shown in FIG. 3 moves the five axis robot 47 to the glass substrate
receiving position. The five axis robot 47 draws the one glass
substrate 33 from the open cassette 35 of the glass substrate
supplying section 34, and set the glass substrate 33 on the
alignment station 53 such that the surface on which the spacers 4
are formed directs upward. The alignment station 53 performs the
tentatively positioning of the glass substrate 33 in the rotational
direction, the X-axis direction and the Y-axis direction.
[0151] The glass substrate 33 to which the tentatively positioning
is completed is draw from the alignment station 53 by the five axis
robot 47. The single axis robot 46 moves the five axis robot 47 to
the joining position with the five axis robot 47 inversing the
suction hand 49 by the fifth axis 50e such that the surface of the
glass substrate 33 on which the spacers 4 are formed directs
downward. The five axis robot 47 at the joining position sets the
glass substrate 33 on the wafer support plate 60 of the underside
joining unit 61 of the joining station 57. The wafer support plate
60 holds the glass substrate 33 by vacuum sucking.
[0152] After setting the glass substrate 33 on the joining station
57, the five axis robot 47 is moved to the wafer receiving
position, the alignment position and the joining position in
sequence by the single axis robot 46, so as to transfer the wafer
25 from the open cassette 28 of the wafer supplying section 26 to
the joining station 57 through the alignment station 53. In the
alignment station 53, the tentatively positioning of the wafer 25
is performed as same as the tentatively positioning of the glass
substrate 33. Because the wafer 25 and the glass substrate 33 are
handled by the robots in the clean booth, it is prevented that
foreign matters stick to the substrates.
[0153] When the glass substrate 33 or the wafer 25 is set on the
joining station 57, as shown in FIG. 16, the topside joining unit
63 is moved to the transcribing station 91 by the single axis robot
93 for the glass substrate. Therefore, as shown in FIG. 11, no
member is inserted between the underside joining unit 61 and the
substrate imaging camera 96 such that the definitely positioning of
the substrates can be performed with using the substrate imaging
camera 96.
[0154] The substrate imaging camera 96 images the glass substrate
33 and outputs the image data to the image processor 98. The image
processor 98 processes the inputted image data to generate binary
data, and outputs the binary data to the control computer 15. The
control computer 15 calculates the position of the glass substrate
33 based on the binary data, and compares the calculated position
to the preinstalled reference position. Then the control computer
15 drives the XY.theta. table 72 according to the difference
between the calculated position and the reference position of the
glass substrate 33 so as to move the wafer support plate 60 such
that the glass substrate 33 is positioned on the reference
position.
[0155] After positioning the glass substrate 33, the topside
joining unit 63 is moved to the joining station 57 by the single
axis robot 93 for the glass substrate. As shown in FIG. 9, the
underside joining unit 61 drives the first to third lifting
actuators 66-68 in synchronization to move the wafer support plate
60 upward to the joining position such that the glass substrate 33
contacts to the glass support plate 62. Then the glass support
plate 62 starts vacuum sucking and the wafer support plate 60 stops
vacuum sucking, therefore the glass substrate 33 is transferred
from the wafer support plate 60 to the glass support plate 62. The
topside joining unit 63 which holds the glass substrate 33 is moved
to the transcribing station 91 again, and the wafer support plate
60 is moved downward to the retract position.
[0156] The five axis robot 47 takes the wafer 25 which completes
the tentatively positioning from the alignment station 53 and set
the wafer 25 on the wafer support plate 60. The wafer 25 is held on
the wafer support plate 60 by vacuum sucking, and is measured its
position in the same method applied to the glass substrate 33, for
performing the definitely positioning.
[0157] As shown in FIG. 16 as double-dashed lines, the transcribing
unit 114 of the transcribing station 91 is moved to the film
receiving position by the single axis robot 115 for transcribing,
and set under the holder 138 of the film supplying section 113 as
shown in FIG. 18. As shown in FIG. 19A, the transcribing unit 114
drives the three transferring actuators 120 in synchronization,
such that the plungers 120a project upward to elevate the
transcribing film 112 from the film case 137.
[0158] As shown in FIG. 19B, the transcribing unit 114 moves from
under the holder 138 of the film supplying section 113 with the
three transferring actuators 120 upholding the transcribing film
112. Then the plungers 120a of the three transferring actuators 120
are moved downward to set the transcribing film 112 on the plate
for transcribing 116. The transcribing film 112 is held on the
plate for transcribing 116 by vacuum sucking. Because the
transferring of the transcribing film 112 is performed in the clean
booth 12 without manual operation, it is prevented that foreign
matters stick to the transcribing film 112. In addition, the
antistatic treatment is applied on the transcribing film 112,
therefore it is prevented that the static electricity adversely
affects handling of the transcribing film 112.
[0159] The transcribing unit 114 which holds the transcribing film
112 by vacuum sucking, moves to the transcribing standby position
of the transcribing station 91. Then as shown in FIG. 20, the plate
for transcribing 116 is moved upward to the transferring position
by the pressurization actuator 121, and as shown in FIG. 21B, the
transcribing film 112 is pressed against the glass substrate 33
held on the glass support plate 62 such that the adhesive 8 is
transcribed to the each spacer 4. After a predetermined time is
passed, the plate for transcribing 116 is moved downward to be
returned to the transcribing standby position. At that time, vacuum
sucking of the transcribing film 112 are stopped for adhering the
transcribing film 112 to the glass substrate 33. Note that because
the transcribing film 112 is pressed against the glass substrate 33
through the cushion, the adhesive 8 can be appropriately adhered on
the spacer 4 without running off from the spacer.
[0160] As shown in FIG. 22, the topside joining unit 63 which holds
the glass substrate 33 and the transcribing film 112 is moved to
the peeling station 92 by the single axis robot 93 for the glass
substrate. Note that as shown in FIG. 23A, the peeling roller 160
is moved downward to the retract position at that time, therefore
the transcribing film 112 does not contact the adhesive tape
153.
[0161] After the movement of the topside joining unit 63 toward the
peeling station 92 is completed, the peeling station 92 drives the
actuator for swing 161 to swing the swing arm 159 to move the
peeling roller 160 to the adhesion position shown in FIG. 23B such
that the adhesive surface 153a of the adhesive tape 153 adheres to
the transcribing film 112. Next, the actuator for swing 161 moves
the peeling roller 160 to the peeling position shown in FIG. 23C
such that the clearance L5 is formed between the adhesive surface
153a of the adhesive tape 153 hanged on the peeling roller 160 and
the under surface of the transcribing film 112.
[0162] As shown in FIG. 24, the peeling station 92 drives the
peeling actuator 149 to move the peeling unit 150 rightward in the
figure, and the winding reel 146 winds the adhesive tape 153 in
synchronization with the movement of the peeling unit. Accordingly,
the transcribing film 112 adhered to the glass substrate 33 is
rolled up to be peeled off from top end thereof by the adhesive
tape 153, such that the layer of the adhesive 8 is formed on the
each spacer 4 by the transcribing as shown in FIG. 21C.
[0163] The curvature and angle of the transcribing film 112 is kept
constant while the peeling operation by the radius R1 of the
peeling roller 160 and the peeling angle .theta.1 determined by the
relative positions of the peeling roller 160 and the guide roller
162. Therefore, it is prevented that the membrane of the adhesive 8
are generated between the glass substrate 33 and the transcribing
film 112, and the membrane bursts to mess the glass substrate 33.
In addition, because the viscosity of the adhesive 8 is properly
controlled by the time process, the wettability for the spacer 4
and the thickness of the layer of the adhesive 8 transcribed on the
spacer 4 can become adequate.
[0164] Because the long adhesive tape 153 is used for peeling the
transcribing film 112, the transcribing film 112 is easily and less
costly held without complicated mechanisms. Also, because the
peeled transcribing film 112 can be wound with the used adhesive
tape 153, complicated mechanisms or devices for processing the
peeled transcribing film 112 are not required. In addition, because
the new adhesive tape 153 can be supplied at once after the used
adhesive tape 153 is wound, efficiency of production of the solid
state imaging device is improved.
[0165] The topside joining unit 63 which holds the glass substrate
33 having the spacers 4 coated by the adhesive 8 is moved toward
the joining station 57 by the single axis robot 93 for the glass
substrate, and is stopped at a position where the substrate imaging
camera 100 faces. The substrate imaging camera 100 images the glass
substrate 33 held by the glass support plate 62 and outputs the
image data to the image processor 98. The image processor 98
generates the binary data by image processing, and outputs the
binary data to the control computer 15. The binary data is used as
a reference for performing the definitely positioning of the wafer
25 against the glass substrate 33.
[0166] After the topside joining unit 63 reached to the joining
station 57, the definitely positioning of the wafer 25 is performed
based on the result of the position measurement of the wafer 25
preformed before and the result of the position measurement of the
glass substrate 33 performed by the substrate imaging camera 100.
Accordingly, the wafer 25 can be joined with glass substrate 33
without misalignment.
[0167] After adjusting the position of the wafer 25, parallelism
adjustment between the wafer 25 and the glass substrate 33 is
performed as shown in FIG. 26. As shown in FIG. 7, in the joining
station 57, the first to third lifting actuators 66-68 are actuated
in synchronization to elevate the wafer support plate 60 on which
the wafer 25 is set and stop the elevation at a position where the
distance S between the wafer 25 and the glass substrate 33 becomes
for example 1 mm.
[0168] Next, the first to third lights 105-107 are turned on to
illuminate the points P1-P3 between the ends of the wafer 25 and
the glass substrate 33. The first to third clearance imaging
cameras 102-104 positioned to face the first to third lights
105-107 image the clearances at the points P1-P3. The image data
from the respective clearance imaging cameras 102-104 are inputted
into the image processor 98. The image processor 98 processes the
image data to generate the binary data, and outputs the binary data
to the control computer 15. The control computer 15 calculates the
clearances L1-L3 at the points P1-P3 based on the binary data.
[0169] If the clearances L1-L3 are equal, the parallelism
measurement is completed without performing the parallelism
adjustment because the joint surfaces of the wafer 25 and the glass
substrate 33 are parallel. If the clearances L1-L3 are not equal,
the parallelism between the wafer 25 and the glass substrate 33
needs to be adjusted.
[0170] The control computer 15 calculates declinations K1-K3
against the predetermined clearance S between the wafer 25 and the
glass substrate 33, by subtracting the clearance S from the
respective measured clearances L1-L3. Then the first to third
lifting actuators 66-68 are respectively actuated according to the
calculated declinations K1-K3, so as to equalize the clearances
L1-L3. After completing the parallelism adjustment, the clearances
L1-L3 is measured again with using the first to third lights
105-107 and the first to third clearance imaging cameras
102-104.
[0171] The parallelism measurement and the parallelism adjustment
are repeated until the measured clearances L1-L3 become equal.
Therefore, the parallelism between the wafer 25 and the glass
substrate 33 can be adjusted with high accuracy. Further, because
the parallelism measurement is performed without contacting the
wafer 25 to the glass substrate 33, the wafer 25 and the glass
substrate 33 cannot be messed. In addition, because the adjusting
the inclination of the wafer 25 is performed in the parallelism
adjustment such that the swingable plate 78 is swung on the joint
surface of the wafer 25 by the first to third plate supporting
mechanisms 73-75, the wafer 25 is not misaligned in horizontal
direction when the parallelism adjustment is performed.
[0172] After the parallelism adjustment, the first to third lifting
actuators 66-68 are actuated in synchronization to move the wafer
25 upward to the joining position where the wafer 25 contacts to
the glass substrate 33, with keeping the inclination of the wafer
25 adjusted by the parallelism adjustment. The wafer 25 which is
pressed to the glass substrate 33 follows the inclination of the
glass substrate 33 such that the wafer support plate 60 is swung by
the first to third plate supporting mechanisms 73-75. Because the
swing of the wafer support plate 60 is preformed on the joint
surface the wafer 25, misalignment caused between the joining
positions of the wafer 25 and the glass substrate 33 can be
minimized. Note that if the pressure of the first to third lifting
actuators 66-68 exceeds the predetermined value, the first to third
pressure control cylinders 69-71 contract such that the excess
pressure escapes. Accordingly, the wafer 25 is prevented from being
locally pushed too hard, which prevents problems of running off the
adhesive 8 from under the each spacer 4 and breaking the wafer
25.
[0173] After passing the predetermined time from joining the wafer
25 and the glass substrate 33, the first to third lifting actuators
66-68 move the wafer support plate 60 downward to the retract
position. At that time, the wafer support plate 60 stops vacuum
sucking for the wafer 25. Accordingly, the wafer 25 joined with the
glass substrate 33 is held by the glass support plate 62. Then the
topside joining unit 63 moves the joined substrate 39 formed by
joining the wafer 25 and the glass substrate 33 toward the
transcribing station 91, and stops the movement at the position
where the substrate imaging camera 100 faces.
[0174] The substrate imaging camera 100 images the joined substrate
39 held by the topside joining unit 63 and outputs the image data
to the control computer 15. The control computer 15 processes the
image data to generate the binary data, and calculates the
alignment of the joining positions of the wafer 25 and the glass
substrate 33. If there is misalignment of the wafer 25 or the glass
substrate 33, the control computer 15 memorizes that the joined
substrate 39 is defective, so as not to send the defective
substrate to manufacturing lines followed after the device for
joining substrates 11.
[0175] After completing the position measuring of the junction by
the substrate imaging camera 100, the topside joining unit 63 is
moved to the transcribing station 91 and is pressed by the plate
for transcribing 116 formed of the cushion. Accordingly, the wafer
25 and the glass substrate 33 are more tightly joined.
[0176] After completing the pressurization of the joined substrate
39 at the transcribing station 91, the joined substrate 39 is moved
to the joining station 57 by the topside joining unit 63, and set
on the wafer support plate 60. Next, the joined substrate 39 is
conveyed from the wafer support plate 60 to the joined substrate
discharging section 40 by the five axis robot 47, so as to be
contained in the substrate case 41. The joined substrate 39 is
ejected from the clean booth 12 with being contained in the
substrate case 41, and fed to a dicer.
[0177] The dicer having a metal-resin bonding blade including
diamond abrasive dices the wafer 25 and the glass substrate 33
joined with the wafer 25 along dicing lines Q and U shown as dashed
lines in FIG. 21D, with cooling the joined substrate 39 by coolant
water. Accordingly, a plurality of the solid state imaging devices
2 is produced by the one operation.
[0178] In the above embodiment, the first to third clearance
imaging cameras 102-104 and the first to third lights 105-107 are
used as substrate clearance measurement section for measuring the
parallelism between the wafer 25 and the glass substrate 33.
However, as shown in FIG. 27, three contour measurement devices 171
using laser beam 170 can be used as the substrate clearance
measurement section. The contour measurement devices 171 emits the
laser beam 170 from a light emitting section 172 to a light
receiving section 173, such that the laser beam 170 passes between
the wafer 25 and the glass substrate 33. Then the clearance between
the wafer 25 and the glass substrate 33 is measured such that
distances of the wafer 25 and the glass substrate 33 from the laser
beam 170 are detected. Note that in case using the contour
measurement device 171, three lifting actuators 175 may be used for
adjusting an inclination of a wafer support plate 174.
[0179] In the above embodiments, the parallelism between the wafer
25 and the glass substrate 33 are measured by detecting the
distance between the wafer 25 and the glass substrate 33. However,
as shown in FIG. 28, the parallelism between the wafer 25 and the
glass substrate 33 can be measured such that laser displacement
gauges 176, 177 measures plural positions of the joint surfaces of
the wafer 25 and the glass substrate 33 in vertical direction and
these measured position are compared to preset reference
positions.
[0180] In this case, displacement amount of the joint surface of
the wafer 25 is measured in a joining station 179, and displacement
amount of the joint surface of the glass substrate 33 is measured
in a measurement station 180 provided next to the joining station
179. Based on the displacement amounts of the joint surfaces of the
substrates, lifting actuators 181 of the joining station 179 are
actuated to adjust the inclination of the wafer 25. Then a glass
support plate 182 is moved to the joining station 179 and the
lifting actuators 181 lifts a wafer support plate 183 such that the
wafer 25 is joined with the glass substrate 33.
[0181] In the above embodiments, the parallelism adjustment is
performed with measuring the clearance or the displacement amount
of the joint surfaces of the wafer 25 and the glass substrate 33.
However, the inclinations of the substrates can be adjusted such
that the one substrate contacts to the other substrate to follow
the inclination of the other substrate. For example, as shown in
FIG. 29A, a spherical shaft 186 is attached on an undersurface of a
wafer support plate 185 which holds the wafer 25. The spherical
shaft 186 is rotatably received by a spherical receiver 187.
[0182] To the spherical receiver 187, one end of an air pipe 188 is
connected and an air pump 189 is connected another end of the air
pipe. When the air pump 189 sends air in the spherical receiver
187, frictional force between the spherical shaft 186 and the
spherical receiver 187 becomes low for allowing movement of the
wafer support plate 185. When the air pump 189 sucks the air in the
spherical receiver 187, the spherical shaft 186 tightly contacts to
the spherical receiver 187 to hold the wafer support plate 185 not
to move.
[0183] First, the air pump 189 sends air in the spherical receiver
187 for allowing movement of the wafer support plate 185. Next, as
shown in FIG. 29B, the glass substrate 185 held on a glass support
plate 191 contacts to the wafer 25 set on the wafer support plate
185. Accordingly, the wafer support plate 185 is moved such that
the wafer 25 follows the inclination of the joint surface of the
glass substrate 33. After that, the air pump 189 sucks the air in
the spherical receiver 187 to hold the wafer support plate 185 not
to move. Then the wafer 25 and the glass substrate 33 are set apart
with keeping the inclinations of the wafer 25 and the glass
substrate 33 in adjusted state. Finally, the adhesive is coated on
the spacers 4 on the glass substrate 33 for joining between the
wafer 25 and the glass substrate 33. Because the parallelism
between the joint surfaces the wafer 25 and the glass substrate 33
are correctly adjusted at this time, the adhesive does not run off
from the spacer 4.
[0184] In the above embodiment, the normal temperature curable
adhesive is used as the adhesive 8, and its viscosity is adjusted
by the time process. However, there are problems that the time
process requires considerable time and that foreign matters may be
adhered to the adhesive while the time process. In considering
these problems, light-delayed curing adhesive for starting curing
when being irradiated with light such as ultraviolet lay can be
used as the adhesive 8. In this case, for example as shown in FIG.
30, an illumination station 200 is provided between the
transcribing station 91 and the film supplying section 113. The
transcribing unit 114 is stopped at the illumination station 200,
and a lump 202 of an illumination device 201 irradiates ultraviolet
ray on the transcribing film 112. Accordingly, the curing of the
adhesive can start before transcribing the adhesive in the
transcribing station 91.
[0185] Although the present invention has been fully described by
way of the preferred embodiments thereof with reference to the
accompanying drawings, various changes and modifications will be
apparent to those having skill in this field. Therefore, unless
otherwise these changes and modifications depart from the scope of
the present invention, they should be construed as included
therein.
INDUSTRIAL APPLICABILITY
[0186] The present invention is applicable to a device for joining
substrates for manufacturing a solid state imaging device. The
present invention is also applicable to a device for joining
substrates for manufacturing other chip size packages which require
joining substrates.
* * * * *